Field of the Invention
The present invention relates to hexagonal ferrite magnetic particles and to a method of manufacturing the same. More particularly, the present invention relates to hexagonal ferrite magnetic particles that are suitable for use as ferromagnetic material in a magnetic recording medium for high-density recording, and to a method of manufacturing the same.
The present invention further relates to magnetic recording powder comprised of the above hexagonal ferrite magnetic particles, and to a magnetic recording medium comprising the above hexagonal ferrite magnetic particles.
Discussion of the Background
Conventionally, ferromagnetic metal magnetic particles have primarily been employed in the magnetic layers of magnetic recording media for high-density recording. Ferromagnetic metal magnetic particles are primarily acicular particles consisting mainly of iron. To achieve high-density recording, efforts have been made to reduce the size of the particles and increase their coercive force. They have been employed in magnetic recording media used in various applications.
With the increase in the amount of information being recorded, ever higher density recording has been demanded of magnetic recording media. However, in achieving even higher density recording, limits to the improvement of ferromagnetic metal magnetic particles have begun to appear. By contrast, magnetic recording media with magnetic layers in which hexagonal ferrite magnetic particles are employed have better high-density characteristics in their vertical components. Accordingly, hexagonal ferrite magnetic particles are ferromagnetic material that is suited to achieving even higher densities. Thus, in recent years, various investigation has been conducted into magnetic recording media employing hexagonal ferrite magnetic particles (for example, Japanese Unexamined Patent Publication (KOKAI) No. 2012-204726 or English language family member US2012/251844A1; Japanese Unexamined Patent Publication (KOKAI) No. 2012-142529 or English language family member US2012/177951A1; Japanese Unexamined Patent Publication (KOKAI) No. 2010-282685; and Japanese Unexamined Patent Publication (KOKAI) No. 2003-296917 or English language family members US2003/143432A1 and U.S. Pat. No. 6,777,073, which are expressly incorporated herein by reference in their entirety).